Tony Hayward, chief executive of BP at a session at the World Economic Forum in Davos wher he spoke of gas extraction from shale. Photograph: Arnd Wiegmann/Reuters

Excitement in the industry over "unconventional" gas supplies has led to a wave of investment in America which Tony Hayward, BP's chief executive, believes could eventually spread around the world.

BP inherited a major stake in shale operations when it took over Amoco 12 years ago, but has added to that by spending $1.75bn buying shale interests from rival Chesapeake Energy in the summer of 2008. Last November BP showed its determination to extend the use of the techniques when it signed a production-sharing agreement with the government of Indonesia to exploit new reserves in Kalimantan.